For many years, certification has been a confusing situation. For every hvac organization there was another certification exam, whether it was the Air Conditioning Contractors of America (ACCA) or the Refrigeration Service Engineers Society (RSES).
The number of different certification tests made it difficult to determine which technicians and contractors were up to par. Within the last few years, organizations such as ACCA, RSES, and several others joined forces to create one industry-supported certification body, known as North American Technician Excellence (NATE).